2.2Assigning Resources to Tasks
The essentials in 30 seconds
- Assigning a resource to a task shows who does what, specifying the units: 100% (full time), 50% (part time), 200% (two people).
- Key relationship: Work = Duration × Units — total effort (person-days) depends on calendar time and the amount of resource.
- Never exceed a resource's maximum capacity: assigning beyond it creates an overallocation (covered at level 3).
Running mini-case — Meriem turns the schedule into a workload plan
Meriem, project manager at an engineering & construction (BTP) company in Algiers, now assigns her resources to the client project tasks. On the 'Structural studies' task, she places 'Structural engineer' at 100%: the 5-day task uses 5 person-days. On 'Site monitoring', she assigns 'Site team' at 50%: the 8 hours of work will spread over 2 days at 4 h/day. Each time she checks the Work column to verify that Work = Duration × Units holds. When she adds a second person to a task, she observes the effect on duration (which depends on the task type, covered in 2.3). Her schedule becomes a genuine workload plan, where every task has an owner and a quantified effort.
Standalone case for this section: it comes back in the lesson, the diagram, the script and the 48h challenge of section 2.2.
1. Who does what (units)
Once resources are created, you assign them to tasks: this is what shows who does what. You assign through the 'Resource Names' column or the 'Assign Resources' dialog. You specify the units: 100% (full time), 50% (part time), 200% (two people). Meriem sees the schedule become a real workload plan.
2. The Work/Duration/Units triangle
Here a fundamental relationship comes in: Work = Duration × Units. Work is total effort (person-days); duration is calendar time; units is the amount of resource. Adding a second person may reduce duration (the work is shared) — or not, depending on the task type (2.3).
3. Keeping it consistent
Understanding this triangle is THE key to making calculations reflect reality. Meriem checks the Work column after each assignment and watches the maximum capacity: assigning someone at 150% when they are full time creates an overallocation. Setting units correctly means reflecting each person's real involvement.
🔎 Concrete example — 🔎 Concrete example — The triangle in action
Do not confuse effort and duration: Meriem calculates an assignment.
Task 4 d x 1 person at 100% = 4 person-days of work.
Add a 2nd person: duration may drop (depending on type).
-> at 50%, 8 h of work spread over 2 days (4 h/day).
Reading : effort (person-days) and duration (calendar) are distinct
Reflex : do not exceed maximum capacity (overallocation)Reading: 8 h of work at 50% spread over 2 days (4 h/day) — the effort does not change, the duration does.
Lesson: every task has an owner and a quantified effort; do not exceed the resource's maximum capacity.
Section vocabulary
- Assignment
- Association of a resource with a task, specifying the share of the resource devoted to that task.
Simple example: Meriem assigns 'Structural engineer' to the 'Structural studies' task.
What it is not: a resource created but never linked to a task.
Reflex: who does the task → assignment.
- Assignment units
- Percentage of resource assigned to the task (100% = full time, 50% = part time, 200% = two units).
Simple example: Meriem assigns 'Site team' at 50% on monitoring.
What it is not: the daily cost rate of a resource.
Reflex: what share of resource → the units.
- Work
- Total effort required, in hours or person-days (to be distinguished from calendar duration).
Simple example: The 4-day task at 100% represents 4 person-days of work.
What it is not: the number of calendar days between start and finish.
Reflex: total effort → work.
- Work/Duration/Units triangle
- Relationship Work = Duration × Units that governs recalculation during assignments.
Simple example: Meriem checks the Work column after each assignment.
What it is not: a relationship between cost and duration, unrelated to effort.
Reflex: one field changes → the others recalculate.
- Workload plan
- Distribution of resource work over time, revealing who is busy and at what level.
Simple example: Meriem reads on her plan who is overloaded next week.
What it is not: a simple Gantt chart without assigned resources.
Reflex: who works when → the workload plan.
In practice — In practice — Assigning resources to tasks
- Select a task and open 'Assign Resources' (Resource tab); choose the resource(s), like Meriem.
- Set the units: 100% for full time on the task, 50% for part time, or several units.
- Look at the Work column: check that Work = Duration × Units holds after the assignment.
- Add a second resource to a task and note the effect on duration (depending on the task type in section 2.3).
Step-by-step script — assigning like Meriem (4 min)
1) Select the 'Structural studies' task and open 'Assign Resources' (Resource tab). 2) Choose 'Structural engineer' and set the units to 100%. 3) Check the Work column: 5 days × 100% = 5 person-days. 4) Assign 'Site team' at 50% on another task and see that 8 h spread over 2 days. 5) Check that no assignment exceeds maximum capacity.
Remember the triangle: when you change one variable, Project recalculates another according to the task type (2.3).
Copy-paste template — my assignment plan
Task Resource Units
Structural studies Structural engineer 100%
Site monitoring Site team 50%
Relationship: Work = Duration x Units
Ex: 8 h at 50% -> 2 days (4 h/day)
Rule: do not exceed max capacity (overallocation)Full time on the task
Meriem assigns 'Structural engineer' at 100%: the task duration will equal the effort in person-days.
Shared part time
Meriem assigns 'Site team' at 50%: 8 h of work spread over 2 days, 4 h per day.
Reinforcement on a task
Meriem adds a second person: duration may drop, depending on the task type (2.3).
Overallocation alert
Meriem sees a 150% assignment on a full-time person: that is an overallocation to fix.
✓ Best practices
- Set the units according to real involvement (100%, 50%…).
- Check that Work = Duration × Units holds.
- Do not exceed a resource's maximum capacity.
✗ Common pitfalls
- Confusing work (effort) with duration (calendar time).
- Assigning a full-time person at 150% (overallocation).
- Being surprised that a duration changes after an assignment (see 2.3).
Key takeaways
- Assigning a resource shows who does the task, with units (100%, 50%, 200%…).
- Key relationship: Work = Duration × Units (effort = time × amount of resource).
- Work is total effort (person-days); duration is calendar time.
- The effect of an assignment on duration depends on the task type (see 2.3).
48h challenge — apply it tomorrow
Like Meriem, assign a resource to a task at 100%, then at 50%, and note in both cases the duration and work obtained. Each time, check that Work = Duration × Units holds, and explain in one sentence why the effort stays the same at 50% while the duration doubles.
- I can assign a resource to a task with the right units.
- I apply and check the Work = Duration × Units relationship.
- I spot an assignment that exceeds maximum capacity.
Frequently asked questions
I added a second person and the duration changed by itself. Is that normal?
Yes, that is the Work/Duration/Units triangle at work: depending on the task type, Project recalculates the variable that is not fixed. Section 2.3 details these types.
What exactly do assignment 'units' mean?
They express the share of the resource devoted to the task: 100% = full time, 50% = part time, 200% = two people. At 50%, a task with 8 h of work spreads over 2 days.
Which relationship governs assignments in Project?